Statement of the 15th IHR Emergency Committee regarding the international spread of poliovirus

The fifteenth meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) regarding the international spread of poliovirus was convened by the Director-General on 14 November 2017 at WHO headquarters with members, advisers and invited member states attending via teleconference.

The Emergency Committee reviewed the data on wild poliovirus (WPV1) and circulating vaccine derived polioviruses (cVDPV). The Secretariat presented a report of progress for affected IHR States Parties subject to Temporary Recommendations. The following IHR States Parties presented an update on the current situation and the implementation of the WHO Temporary Recommendations since the Committee last met on 3 August 2017: Afghanistan, the Democratic Republic of Congo (DR Congo), Nigeria, Pakistan and the Syrian Arab Republic.

Wild polio

Overall the Committee was encouraged by continued steady progress in all three WPV1 infected countries, Afghanistan, Nigeria and Pakistan and the fall in the number of cases globally, and that international spread remained limited to between Afghanistan and Pakistan only. While falling transmission in these three countries decreased the risk of international spread, the consequences of any failure to prevent spread would increasingly be a set-back to eradication and a risk to public health, as funding winds down in the coming years.

The Committee commended the high level commitment seen in both Afghanistan and Pakistan, and the high degree of cooperation and coordination, particularly targeting the high risk mobile populations that cross the international border, such as nomadic groups, local populations straddling the border, seasonal migrant workers and their families, repatriating refugees (official and informal), and guest children (children staying with relatives across the border). Stopping transmission in these populations remains a major challenge that cannot be under-estimated, underlining the critical continuing need for cross border activities in surveillance and vaccination.

The Committee commended the achievements in Pakistan that have resulted in the number of cases falling to just five so far in 2017; achievements included the improved accessibility, improved communication to reduce missed children and better quality supplementary immunization activities (SIA). However, WPV1 transmission continues to be widespread geographically as detected by environmental surveillance and this remains a source of major concern, notwithstanding that the intensity of environmental surveillance is now higher than previously, meaning the probability of environmental detection is now higher.

The Committee was concerned by the ongoing risks to eradication posed by the number of inaccessible and missed children in Afghanistan, particularly in the southern region resulting in ten cases to date in 2017.

The Committee was impressed by the innovations that continue to be made in Nigeria to reach children in Borno, but was very concerned that although the number of inaccessible settlements has fallen, there remains a substantial population in Borno state that is totally inaccessible, including around 160,000 – 200,000 children aged under five. The Committee concluded that there is a substantial risk that polioviruses are still circulating in these inaccessible areas. Nigeria also reported on ongoing efforts to ensure vaccination at international borders (including at airports), other transit points, IDP camps and in other areas where nomadic populations existed, but the Committee felt that efforts to date were inadequate. The Committee also noted that routine immunization, particularly in high risk areas of northern Nigeria, is performing poorly and along with polio eradication has been made a national priority. Although it is over 13 months since the last detection of WPV1 in Nigeria, the recent outbreak response assessment by global polio experts concluded ongoing transmission could not be ruled out.

There was ongoing concern about the Lake Chad basin region, and for all the countries that are affected by the insurgency, with the consequent lack of services and presence of IDPs and refugees. The risk of international spread from Nigeria to the Lake Chad basin countries or further afield in sub-Saharan Africa remains high. The Committee was encouraged that the Lake Chad basin countries including, Cameroon, Chad, the Central African Republic (CAR), Niger and Nigeria continued to be committed to sub-regional coordination of immunization and surveillance activities. However, there is concern about the Lake Chad islands which are currently inaccessible and also about significant gaps in population immunity exist in some areas of these countries in border areas with Borno, and the ongoing population movement in the sub-region was a major challenge.

Vaccine derived poliovirus

The Committee commended the efforts made in some very challenging circumstances in DR Congo and the Syrian Arab Republic. These outbreaks highlighted the presence of vulnerable under-immunized populations in areas with inaccessibility, either due to conflict or geographical remoteness. Furthermore, the delay in detection of these outbreaks illustrated that serious gaps in surveillance exist in many areas of the world, often related to weak health systems or to conflict resulting in disrupted health systems.

In DRC, there has been transmission after the initial SIA’s with geographical spread outside the health zones covered, into Tanganyika, necessitating further rounds with mOPV2. Risks are compounded by poor surveillance in many areas, and widespread gaps in population immunity.

The Committee was very concerned by the size of the outbreak in the Syrian Arab Republic, and the difficulty of reaching target populations because of the conflict. As type 2 population immunity rapidly wanes, the risk of spread within the Syrian Arab Republic and beyond its borders will increase substantially, meaning urgent action is needed to stop transmission. The Committee commended countries surrounding the outbreak zone that are responding to prevent importation, particularly among Syrian refugees in Lebanon, Jordan, and Turkey. The Committee urged any country receiving Syrian refugees, particularly from Deir Ez-Zor and Raqqa, to ensure polio vaccination with IPV.

The Committee noted with concern the recent detection of a single highly diverged VDPV2 in sewage in Mogadishu in Somalia, with genetic evidence of more than three years of replication without detection.

Conclusion

The Committee unanimously agreed that the risk of international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC), and recommended the extension of revised Temporary Recommendations for a further three months. The Committee considered the following factors in reaching this conclusion:

• The potential risk of further spread through population movement, whether for family, social or cultural reasons, or in the context of populations displaced by insecurity, returning refugees, or nomadic populations, and the need for international coordination to address these risks, particularly between Afghanistan and Pakistan, Nigeria and its Lake Chad neighbors, and countries bordering the Syrian Arab Republic.

• The current special and extraordinary context of being closer to polio eradication than ever before in history, with the incidence of WPV1 cases in 2017 the lowest ever recorded.

• The risk and consequent costs of failure to eradicate globally one of the world’s most serious vaccine preventable diseases. Even though global transmission of WPV1 has fallen dramatically and with it the likelihood of international spread, the consequences and impact of international spread should it occur now would be grave and a major set-back to achieving eradication.

• The risk of global complacency developing as the numbers of polio cases continues to fall and eradication becomes a tangible reality soon.

• The outbreak of WPV1 (and cVDPV) in Nigeria highlighting that there are high-risk areas where surveillance is compromised by inaccessibility, resulting in ongoing circulation of WPV for several years without detection. The risk of transmission in the Lake Chad sub-region appears high.

• The serious consequences of further international spread for the increasing number of countries in which immunization systems have been weakened or disrupted by conflict and complex emergencies. Populations in these fragile states are vulnerable to outbreaks of polio. Outbreaks in fragile states are exceedingly difficult to control and threaten the completion of global polio eradication during its end stage.

• The importance of a regional approach and strong cross­border cooperation, as much international spread of polio occurs over land borders, while also recognizing that the risk of distant international spread remains from zones with active poliovirus transmission.

• Additionally with respect to cVDPV:

cVDPVs also pose a risk for international spread, which without an urgent response with appropriate measures threatens vulnerable populations as noted above;

The large number of cases in the Syrian outbreak within a short space of time and close to the international border with Iraq in the context of ongoing population movement because of conflict, considerably heightens the risk of international spread;

The ongoing circulation of cVDPV2 in DR Congo, Nigeria, Pakistan and the Syrian Arab Republic demonstrates significant gaps in population immunity at a critical time in the polio endgame;

The ongoing urgency to prevent type 2 cVDPVs following the globally synchronized withdrawal of the type 2 component of the oral poliovirus vaccine in April 2016, noting that population immunity to type 2 polioviruses is rapidly waning;

The ongoing challenges of improving routine immunization in areas affected by insecurity and other emergencies;

The global shortage of IPV which poses an additional risk.

Risk categories

The Committee provided the Director-General with the following advice aimed at reducing the risk of international spread of WPV1 and cVDPVs, based on the risk stratification as follows:

States infected with WPV1, cVDPV1 or cVDPV3, with potential risk of international spread.

States infected with cVDPV2, with potential risk of international spread.

States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV.

Criteria to assess States as no longer infected by WPV1 or cVDPV

Poliovirus Case: 12 months after the onset date of the most recent case PLUS one month to account for case detection, investigation, laboratory testing and reporting period OR when all reported AFP cases with onset within 12 months of last case have been tested for polio and excluded for WPV1 or cVDPV, and environmental or other samples collected within 12 months of the last case have also tested negative, whichever is the longer.

Environmental or other isolation of WPV1 or cVDPV (no poliovirus case): 12 months after collection of the most recent positive environmental or other sample (such as from a healthy child) PLUS one month to account for the laboratory testing and reporting period.

These criteria may be varied for the endemic countries, where more rigorous assessment is needed in reference to surveillance gaps (eg Borno).

Once a country meets these criteria as no longer infected, the country will be considered vulnerable for a further 12 months. After this period, the country will no longer be subject to Temporary Recommendations, unless the Committee has concerns based on the final report.

Temporary recommendations

States infected with WPV1, cVDPV1 or cVDPV3 with potential risk of international spread: Afghanistan, Pakistan, Nigeria.

These countries should:

• Officially declare, if not already done, at the level of head of state or government, that the interruption of poliovirus transmission is a national public health emergency and implement all required measures to support polio eradication; where such declaration has already been made, this emergency status should be maintained.

• Ensure that all residents and long­term visitors (i.e. > four weeks) of all ages, receive a dose of bivalent oral poliovirus vaccine (bOPV) or inactivated poliovirus vaccine (IPV) between four weeks and 12 months prior to international travel.

• Ensure that those undertaking urgent travel (i.e. within four weeks), who have not received a dose of bOPV or IPV in the previous four weeks to 12 months, receive a dose of polio vaccine at least by the time of departure as this will still provide benefit, particularly for frequent travelers.

• Ensure that such travelers are provided with an International Certificate of Vaccination or Prophylaxis in the form specified in Annex 6 of the IHR to record their polio vaccination and serve as proof of vaccination.

• Restrict at the point of departure the international travel of any resident lacking documentation of appropriate polio vaccination. These recommendations apply to international travelers from all points of departure, irrespective of the means of conveyance (e.g. road, air, sea).

• Further intensify cross­border efforts by significantly improving coordination at the national, regional and local levels to substantially increase vaccination coverage of travelers crossing the border and of high risk cross­border populations. Improved coordination of cross­border efforts should include closer supervision and monitoring of the quality of vaccination at border transit points, as well as tracking of the proportion of travelers that are identified as unvaccinated after they have crossed the border.

• Further intensify efforts to increase routine immunization coverage, including sharing coverage data, as high routine immunization coverage is an essential element of the polio eradication strategy, particularly as the world moves closer to eradication.

• Maintain these measures until the following criteria have been met: (i) at least six months have passed without new infections and (ii) there is documentation of full application of high quality eradication activities in all infected and high risk areas; in the absence of such documentation these measures should be maintained until the state meets the above assessment criteria for being no longer infected.

• Provide to the Director-General a regular report on the implementation of the Temporary Recommendations on international travel.

• Officially declare, if not already done, at the level of head of state or government, that the interruption of poliovirus transmission is a national public health emergency and implement all required measures to support polio eradication; where such declaration has already been made, this emergency status should be maintained.

• Noting the existence of a separate mechanism for responding to type 2 poliovirus infections, consider requesting vaccines from the global mOPV2 stockpile based on the recommendations of the Advisory Group on mOPV2.

• Encourage residents and long­term visitors to receive a dose of IPV (if available in country) four weeks to 12 months prior to international travel; those undertaking urgent travel (i.e. within four weeks) should be encouraged to receive a dose at least by the time of departure.

• Ensure that travelers who receive such vaccination have access to an appropriate document to record their polio vaccination status.

• Intensify regional cooperation and cross­border coordination to enhance surveillance for prompt detection of poliovirus, and vaccinate refugees, travelers and cross­border populations, according to the advice of the Advisory Group.

• Further intensify efforts to increase routine immunization coverage, including sharing coverage data, as high routine immunization coverage is an essential element of the polio eradication strategy, particularly as the world moves closer to eradication.

• Maintain these measures until the following criteria have been met: (i) at least six months have passed without the detection of circulation of VDPV2 in the country from any source, and (ii) there is documentation of full application of high quality eradication activities in all infected and high risk areas; in the absence of such documentation these measures should be maintained until the state meets the criteria of a ‘state no longer infected’.

• At the end of 12 months without evidence of transmission, provide a report to the Director-General on measures taken to implement the Temporary Recommendations.

States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV

• Enhance surveillance quality, including considering introducing supplementary methods such as environmental surveillance, to reduce the risk of undetected WPV1 and cVDPV transmission, particularly among high risk mobile and vulnerable populations.

• Enhance regional cooperation and cross border coordination to ensure prompt detection of WPV1 and cVDPV, and vaccination of high risk population groups.

• Maintain these measures with documentation of full application of high quality surveillance and vaccination activities.

• At the end of 12 months* without evidence of reintroduction of WPV1 or new emergence and circulation of cVDPV, provide a report to the Director-General on measures taken to implement the Temporary Recommendations.

*For the Lake Chad countries, this will be linked to when Nigeria is considered no longer infected by WPV1 or cVDPV2. Based on the last cases (above) reports will be due for Guinea in January 2018, and in Lao People’s Democratic Republic in February 2018.

Additional considerations

The Committee noted that in all the infected and vulnerable countries, routine immunization was generally quite poor, if not nationally, then in sub-national pockets. The Committee strongly encourages all these countries to make further efforts to improve routine immunization, and requested international partners to support these countries in rapidly improving routine immunization coverage to underpin eradication.

The Committee also strongly encouraged countries newly infected with WPV or cVDPV to act with a great degree of urgency in responding to outbreaks as national public health emergencies, and to ensure emergency operations are used to facilitate this accelerated response.

The Committee also urged that Nigeria and the Lake Chad countries increase cross border efforts and joint planning and response. Intensified effort is needed to identify and reach vulnerable populations in the sub-region, particularly in the Lake Chad islands. Noting the low number of international travelers being vaccinated in Nigeria, the committee recommended that the country needs to improve implementation of the Temporary Recommendations regarding traveler vaccination, including reporting of achievements.

The Committee urged all countries to avoid complacency which could easily lead to a resurgence of polio. Surveillance particularly needs careful attention so that new transmissions are rapidly detected. In particular careful assessment is required where insecurity and inaccessibility impact on surveillance. The secretariat was requested to provide a report on what is being done to track populations where there are high proportions of unvaccinated children due to inaccessibility.

The Committee noted that progress has been made in IPV supply in Ukraine, and requested to be kept updated on the situation with respect to immunization activities resulting from this. The Committee also requested an update on the situation in Somalia at its next meeting.

Based on the current situation regarding WPV1 and cVDPV, and the reports made by Afghanistan, DR Congo, Nigeria, Pakistan, and the Syrian Arab Republic, the Director-General accepted the Committee’s assessment and on 20 November 2017 determined that the situation relating to poliovirus continues to constitute a PHEIC, with respect to WPV1 and cVDPV.

The Director-General endorsed the Committee’s recommendations for countries meeting the definition for ‘States infected with WPV1, cVDPV1 or cVDPV3 with potential risk for international spread’, ‘States infected with cVDPV2 with potential risk for international spread’ and for ‘States no longer infected by WPV1 or cVDPV, but which remain vulnerable to re-infection by WPV or cVDPV’ and extended the Temporary Recommendations under the IHR to reduce the risk of the international spread of poliovirus, effective 20 November 2017.